Well cross-over apparatus for selective communication of flow passages in a well installation

ABSTRACT

A well flow system, including one or more flow conductors disposed in a well having a casing annulus, means interconnecting the conductor or conductors and/or annulus, and a fluid-actuated valve in at least one of the flow conductors for selectively communicating the conductor or conductors and/or the annulus of the well responsive to a pressure differential applied across the valve and controlled from the surface. The flow system is adapted to well producing and well treating procedures. A number of different flow conductor, well annulus and valve arrangements are shown with provision in each system disclosed for hydraulic control of a downhole valve to communicate selected combinations of flow passages of the conductors and the well annulus.

Sizer et a1.

[ Reissued Oct. 28, 1975 1 WELL CROSS-OVER APPARATUS FOR SELECTIVE COMMUNICATION OF FLOW PASSAGES IN A WELL INSTALLATION [75] Inventors: Phillip S. Sizer; Albert W. Carroll,

both of Dallas, Tex.

[73] Assignee: Otis Engineering Corporation, Dallas, Tex.

[22] Filed: Mar. 14, 1974 [21] Appl. N0.: 451,005

Related U.S. Patent Documents 3,494,420 2/1970 Sizer 166/313 3,533,430 10/1970 Fredd 166/224 3,552,491 1/1971 Thompson... 166/313 3,554,281 l/1971 Ecuer 166/224 3,606,584 9/1971 Sizer 166/313 3,680,637 8/1972 Raulins 166/313 Primary ExaminerJames A, Leppink Attorney, Agent, or Firm-Joe E. Edwards, Esq.; M. H. Gay, Esq.; Jack R. Springgate, Esq.

[5 7] ABSTRACT A well flow system, including one or more flow conductors disposed in, a well having a casing annulus, means interconnecting the conductor or conductors and/or annulus, and a fluid-actuated valve in at least one of the flow conductors for selectively communicating the conductor or conductors and/or the annulus of the well responsive to a pressure differential applied across the valve andcontrolled from the surface. The flow system is adapted to well producing and well treating procedures. A number of different flow conductor, well annulus and valve arrangements are shown with provision in each system disclosed for hydraulic control of a downhole valve to communicate selected combinations of flow passages of the conductors and the well annulus.

25 Claims, 32 Drawing Figures Reissued Oct. 28, 1975 Sheet 1 of 11 50 an r62 54 "I /70 63: as

345 s Fig.25 i

INVENTORS Phllhp S. Sizer BY Albea iWLf-orroH AT TORNEY Reissued 0st. 28, 1975 Shem 2 of 11 Re. 28,588

Fig.6 Fig.7

INVENTORS Phillip S. Sizer BY Albert W. Carroll ATTORNEY Reissued Oct. 28, 1975 Sheet 3 of 11 Re. 28,588

fl m u *W /55 V j /fia i I A I56 w E/I/6/Q V- F|g.8 Fig.9

,INVENTORS Phillip S. Sizer BY Albert W. Carroll ATTORNEY Reissued Oct. 28, 1975 SheetS ofll Re. 28,588

INVENTORS Phillip Sizer BY Albert W.C0rroll WEN ATTORNEY Reissued Oct. 28, 1975 Sheet 7 of 11 Re. 28,588

INVENTOR8 Phillip S. Sizer BY Albert W. Corroil QWEM ATTORNEY Reissued Oct. 28, 1975 Sheet 8 of 11 Phillip S. Sizer BY Allitl'f w. COUCH ATTORNEY Reissued OCt. 28, 1975 Sheet 9 of 11 Re. 28,588

Fig.2l

INVENTORS PhIHip S. Sizer Alber1.W. Carroll Reissued Oct. 28, 1975 Fig.23

Sheet 10 of 11 Fig.24

BY A?! crt W. Corroli wmw3nm ATTORNEY Reissued Oct. 28, 1975 Sheet 11 of 11 R63. 28,588

INVENTORS Phillip S. Sizer Alberl W. Carroll WMQQM ATTORNEY WELL CROSS-OVER APPARATUS FOR SELECTIVE COMMUNICATION OF FLOW PASSAGES IN A WELL INSTALLATION Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to well tools, and more particularly relates to well flow systems for remote hydraulic control of flow in passages in a well bore.

More and more, sought-after earth fluids, such as oil and gas, become increasingly difficult to find and produce and, when found, are often in remote, physically inaccessible locations. One preferred approach to a solution to the more trying circumstances of such problems resides in a well flow system which is remotely controllable and which may include means for fluid transport of some of the control mechanism employed, such as the fluid operated valves to and from the downhole equipment from the surface. Accordingly, it is a particularly important object of the invention to provide a new and improved well flow system for flow control between selected flow paths in a well.

It is another object of the invention to provide a well flow control system which is manipulated from the surface by fluid pressure means.

It is another object of the invention to provide a well system in which control valves may be pumped to and from operating locations in a well.

It is a further object of the invention to provide a Well flow control system including valve means which are opened and closed responsive to fluid pressure differ entials applied within a well bore between selected flow passages in the bore.

It is another object of the invention to provide a well flow control system in which fluid communication is controllable through at least one flow conductor in the well above a packer and a portion of the flow conductor communicating with a producing formation around the well below the packer.

It is another object of the invention to provide a well flow system which includes at least one flow conductor for producing well fluids from a well bore and at least one other flow passage selectively communicated with the flow conductor for applying a pressure differential to valve means in the flow conductor for controlling the function of such valve means.

It is still another object of the invention to provide a well flow system including a plurality of flow passages defined by a flow conductor communicating through a valve to a packed-off producing formation, a flow conductor extending to such valve for use in controlling such valve, and a flow conductor connected with an annulus portion in the bore of the well isolated from the producing formation.

It is still another object of the invention to provide a well flow system including a flow conductor communicating through a valve to a packed-off producing formation, such flow conductor also communicating through the valve to an annulus in the well bore isolated from the producing formation, and a flow conductor connected with the annulus for pressure control of the valve by adjustment of a pressure differential between the first flow conductor and the annulus.

It is still another object of the invention to provide a well flow system including at least two flow conductors in a well bore communicating with each other through a fluid pressure controllable valve and communicating through such valve with the annulus of the well and including a flow conductor communicating with the annulus whereby a pressure differential may be applied at the valve between either of the flow conductors communicating and between the annulus and the flow conductor.-

It is still another object of the invention to provide a well flow system including at least two flow conductors one of which includes a pressure controllable valve through which such conductor communicates with the other flow conductor, both of such conductors communicating with the well bore below such valve and another flow conductor communicating with the annulus of the well bore around the first two mentioned flow conductors.

It is still another object of the invention to provide a well flow system including at least two flow conductors one of which has a fluid operated valve with a bypass around such valve, the valve isolating the flow conductors from each other at one position and at another position communicating the flow conductors while shutting off a portion of one conductor below the valve.

It is still another object of the invention to provide a well flow system including at least two flow conductors interconnected through a fluid-actuated valve, the flow conductor in which the valve is positioned having a bypass around the valve, the portion of such flow conductor communicating from above the valve through the valve with the other flow conductor, while the portion of such flow conductor below the valve is isolated from the other flow conductor, the valve being operable responsive to a differential pressure between the flow conductors.

It is another object of the invention to provide a well system having first and second flow conductors, a cross-over between the conductors, and a valve in the first flow conductor isolating the conductors at one position and communicating the conductors at another position while shutting off the first conductor below the valve, the casing being isolated at all times, the valve functioning responsive to a casing-first conductor pressure differential.

It is another object of the invention to provide a well flow system having interconnected first and second flow conductors communicating through a valve in the first flow conductor and having a bypass along such first flow conductor around the valve, the valve being operable responsive to a pressure differential between the casing annulus pressure and pressure in the first flow conductor, the flow conductors being isolated from each other and from the casing at one valve position, and the second of the flow conductors being communicated with the casing annulus and the lower portion of the first conductor isolated at a second valve position.

It is still another object of the invention to provide a well flow system including at least a' pair of interconnected flow conductors with a fluid-actuated valve in the first of such flow conductors and a bypass in such conductor around the valve, the valve isolating the flow conductors from each other at one valve position while the portion of the first flow conductor above the valve is communicated through the valve with the casing annulus and the portion of the first conductor below the valve is isolated at a second valve position.

It is still another object of the invention to provide a well flow system including at least a pair of interconnected flow conductors, a first of such flow conductors including a fluid-actuated valve and having a bypass around such valve, the flow conductors being isolated from each other at a first valve position, the casing an nulus being isolated at all times, and the valve being moved to a second position responsive to casing pressure to communicate the flow conductors and isolate the portion of the first flow conductor below the valve.

It is still another object of the invention to provide a well flow system having at least a pair of flow conductors interconnected, the first of such conductors having a casing pressure responsive fluid-operated valve and a bypass around the valve, the casing annulus, the first flow conductor above the valve, and the second flow conductor being simultaneously communicated through the valve while the first flow conductor below the valve is isolated from the casing annulus and the second flow conductor.

It is still another object of the invention to provide a well flow system having at least a pair of flow conductors interconnected through a fluid operated valve disposed in a first of the flow conductors and including a sliding sleeve valve disposed in the second of the flow conductors for isolating the two flow conductors at the valve from each other, the first of the flow conductors having bypass flow passages around the valve, the flow conductors above the valve being communicated with each other when the valve is at a lower position with the lower portion of the first flow conductor below the valve being isolated, and the flow conductors being fully isolated from each other when the valve is in an up position.

It is still another object of the invention to provide a well flow system having at least two flow conductors interconnected through a fluid-operated valve disposed in one of the flow conductors, each of the flow conductors having landing and locking recess means for placing a valve in either of the flow conductors at a crossover connection between them, each of the flow conductors having a bypass around the landing means for bypassing the valve when placed in either of the flow conductors, the valve being adapted to permit communication between the two flow conductors while isolating the portion of the flow conductor containing the valve below the valve from the upper portion of such flow conductor and from the other flow conductor, the valve being operable responsive to a pressure differential between the flow conductors, and the flow conductors being isolated from the casing annulus.

It is another object of the invention to provide a well system having first and second flow passages, a valve in the first passage for isolating the passages at a first valve position while allowing flow along the first passage and for communicating the passages at a second valve position responsive to a pressure exterior of the first passage while isolating the first passage below the valve.

It is another object of the invention to provide a well valve arrangement for use in a well flow control system which includes a side-pocket type landing nipple in one flow conductor connected through a cross-over flow passage with another flow conductor whereby a valve in the side pocket controls communication between the flow conductors.

It is another object of the invention to provide a valve arrangement for a well system including a pair of laterally spaced side-pocket type landing nipples included in first and second flow conductors and connected by a cross-over passage whereby a flow control valve may be disposed in the side pocket of either of the landing nipples for controlling fluid communication between the flow conductors.

It is another object of the invention to provide a well arrangement including side-pocket landing nipples in spaced tubing strings arranged in an over-under nested relationship and interconnected by a flow tube for communicating the tubing strings with each other through the side pockets whereby a valve disposed in either of the side pockets selectively controls communication between the tubing strings through the side pockets.

It is another object of the invention to provide a body member for use with laterally spaced tubing strings and including a side-pocket type landing nipple along one side of the body and a longitudinal flow passage along the other side communicated with the landing nipple at the side pocket by a lateral flow passage for selectively communicating the tubing strings connected with the body by means of a flow control valve disposed in the side pocket.

It is another object of the invention to provide a body member having a pair of laterally spaced side-pocket type landing nipples formed therein and a cross-over flow passage communicating the nipples at the side pockets whereby fluid flow is controllable between the spaced landing nipples by a valve placed in either of the side pockets for selectively communicating parallel tubing strings connected with the body.

These and further objects of the invention will be apparent from reading the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a fragmentary schematic view in longitudinal section of a well having a How system in accordance with the invention;

FIG. 2 is a view similar to FIG. 1 of another form of well flow system embodying the invention;

FIG. 3 is a view similar to FIG. 1 of a still further form of well flow system embodying the invention;

FIG. 4 is a view similar to FIG. 1 of another form of well flow system embodying the invention;

FIG. 5 is a fragmentary view in longitudinal section of one form of valve which may be used in the well systems of FIGS. l4 for flow control between the flow passages defined in the well systems.

FIG. 6 is a schematic view in longitudinal section of another well valve which may be employed in the well systems of FIGS. 1-4 showing the valve at an upper end position;

FIG. 7 is a view similar to FIG. 6 showing the well valve at a lower end position;

FIG. 8 is a longitudinal fragmentary view in section of flow conductors and a well valve in a system similar to that shown in FIG. 4 with the valve at an upper end position;

FIG. 9 is a view similar to FIG. 8 with the valve moved to a lower end position;

FIG. 10 is a fragmentary longitudinal sectional view of flow conductors and a well valve for a system similar to that of FIG. 4 showing the well valve at an upper end position;

FIG. 11 is a view similar to FIG. with the valve moved to a lower end position;

FIG. 12 is a longitudinal fragmentary sectional view of another flow conductor and well valve arrangement for a system similar to FIG. 3 showing the valve at an upper end position;

FIG. 13 is a view similar to FIG. 12 illustrating the valve at a lower end position;

FIG. 14 is a fragmentary longitudinal sectional view of another flow conductor and well valve arrangement for a system similar to FIG. 3 with the valve at an upper end position;

FIG. 15 is a view similar to FIG. 14 with the valve moved to a lower end position;

FIG. 16 is a longitudinal sectional view of another flow conductor and well valve arrangement for a well system similar to FIG. 3 with the valve at an upper end position;

FIG. 17 is a view similar to FIG. 16 with the valve moved to a lower end position;

FIG. 18 is a longitudinal fragmentary sectional of another arrangement of flow conductors and well valve for a well system similar to FIG. 3 showing the valve at an upper end position;

FIG. 19 is a view similar to FIG. 18 with the valve moved to a lower end position;

FIG. 20 is a longitudinal fragmentary sectional view of another arrangement of flow conductors and a well valve for a well flow system similar to FIG. 3 showing the valve at an upper end position;

FIG. 21 is a view similar to FIG. 20 showing the valve moved to a lower end position;

FIG. 22 is a longitudinal fragmentary sectional view of a still further form of flow conductor and well valve arrangement for a system similar to that of FIG. 3 utilizing a sliding sleeve valve in one flow conductor and a fluid responsive control valve in the other flow conductor, showing the valve at an upper end position;

FIG. 23 is a fragmentary longitudinal view in section of a portion of the wall system of FIG. 22 with the well valve removed and the sliding sleeve valve moved upwardly to a closed position;

FIG. 24 is a fragmentary longitudinal view in section of another form of flow conductor and well valve arrangement including a bypass along each flow conductor and means for locking the well valve in either of the flow conductors; and

FIG. 25 is a broken, longitudinal, fragmentary view in section of a side pocket form of landing nipple for a well control valve.

FIG. 26 is a broken longitudinal fragmentary view in section of a side-pocket landing nipple in one tubing string connected by a cross-over to another tubing string;

FIG. 27 is a broken longitudinal fragmentary view in section of interconnected side-pocket type landing nipples included in adjacent tubing strings ofv a well;

FIG. 28 is a broken fragmentary longitudinal view in section of an over-under arrangement of interconnected side-pocket type landing nipples in adjacent tubing strings;

FIG. 29 is a broken fragmentary longitudinal view in section of a unitary body member having a side-pocket type landing nipple formed along one side and an interconnected longitudinal bore defining a flow passage along the other side for use with parallel tubing strings;

FIG. 30 is a view in section along the line 30-30 of FIG. 29;

FIG. 31 is a broken fragmentary longitudinal view in section along the line 31-31 of FIG. 32 of another unitary body structure for use with parallel tubing strings in a well and including a side-by-side arrangement of interconnected side-pocket type landing nipples; and

FIG. 32 is a cross-sectional view along the line 32-32 of FIG. 31 showing the actual side-by-side positions of the two landing nipples of FIG. 31.

In accordance with the invention, a number of forms of a well system embodying the invention are provided for well production and servicing. In its broadest concept the well system has a flow conductor defining a first flow passage for-well fluids flow and for well service fludis flow at separate selected times. One or more other flow passages are provided in the well system. At least two of the flow passages communicate through a valve operable in the first flow passage. At a first valve position such two passages are isolated from each other while flow is permitted to the surface through at least the first passage from below the valve. At a second valve position two of the flow passages communicate with each other. The pressure in the first flow passage is normally above the other flow passage pressures to which the valve is exposed. The valve is moved from a first to a second position responsive to an increase in pressure from exterior of the first flow passage. At the second valve position various well servicingprocedures are carried out.

Referring to FIG. 1, a well system 40 includes a well 41 having a well casing 42 provided with a surface well head 43. A flow conductor 44 is supported in the well for producing well fluids and for introducing fluids into the well during treatment procedures. The flow conductor includes a surface control valve 45. A downhole valve 50 is included in the flow conductor for controlling flow through the conductor to the surface and for providing one leg of a closed circuit flow path above the valve for tool pumping and well servicing purposes. A fluid control line 51 having a surface valve 52 is connected through the well head into the valve 50 for fluid pressure control of the valve 50 and to provide a return flow path to the surface for certain well servicing and tool pumping functions. A suitable well packer 53 seals around the flow conductor within the casing below the valve 50 defining with the flow conductor and easing an upper well annulus 54 and a lower well fluids producing portion 55. A line 60 having a valve 61 is connected through the well head into the annulus 54 for fluid flow to and from the annulus for various well control and servicing purposes.

The valve 50 as shown in greater detail in FIG. 5 includes a housing 62 which may be formed integral with a section of the flow conductor 44 or may be provided with connection means, such as threads at opposite ends, not shown, so that the valve may be installed in any suitable location along the length of the flow conductor 44 by threadedly engaging the housing between adjacent sections of the conductor. The valve has an internal concentrically disposed cylindrical body 63 provided with a longitudinal bore 64. The body 63 is inwardly spaced in the valve housing 50 defining an annulus 65 extending substantially the length of the valve between the body and housing. The annulus 65 is closed at the lower end and open to the conductor 44.

t the upper end. The body is connected by short onduit portion "ill to the housing of?! defining a flow assage or side port '71 from exterior of the valve housig into the central bore ti t. in the well system ll], the ontrol [in] line 51 is connected into the side port 1. The bore lid is enlarged along a lower portion Y3 long which the body n3 is provided with side ports '73 ommunicating the central bore of the valve with the .nnulus 65 so that tluid may flow from the flow conluctor below the valve through the valve into the flow onductor above the valve. Upper and lower valve eats "Ml and 75, respectively, are formed in the valve iody 63 at the opposite ends of the central bore portion '2 to receive a ball valve llll which is movable between he upper and lower positions illustrated in A emovable plug lll is loci-ted in the upper end portion )f the bore 64- by locking dogs ll'ti which engage an in ernal annular locking recess in the body 63 around the )OTC M. A ring seal lid supported on the plug ls l seals u'ound the plug with the wall of the bore it will be 1 ipparent that the body till could be fabricated with a solid closure at the upper end of the bore ti l to perform be same function as the plug ill so that fluids in the acre 64 are directed to the side port ill of the valve. At :he lower position of the ball valve hil shown in solid ines in FIG. 5 no flow may occur through the valve :lownwardly into the flow conductor portion l la below :he valve. At the upper position illustrated by the bro-- sen line representation of the ball valve in PM}. 5, flow may not occur through the valve in the central bore to the side port "7i in the valve.

The well system ill allows well production upwardly through the flow conductor i l and valve llll from the well bore portion 55 below the paclter 53. Also, the system permits closing the llow conductor at the valve so there is no fluid communication to the lower producing portion of the well bore while a closed circuit fluid flow pattern is established in the well including the flow conductor 44 above the valve till and the line ill. When the pressure in the producing portion of the well bore below the packer, as communicated in the open lower end 44a of the flow conductor below the valve lid, is greater than the pressure in the line fill and the flow conductor dd above the valve fill, the ball valve is forced to an upper end position against the seat till 74, closing off the bore dd through the valve so that well fluids being produced lflow upwardly into the lower end 44a of the flow conductor into the valve till and ra dially outwardly through the ports below the ball r valve. The fluids then flow upwardly in the annulus oh into the flow conductor ll l above the valve to the sur face. When it is desired to shut oil? production flow through the valve fill, the valve li may be closed, and with the valve till open, the pressure may be in eased through the control line till until the ball valve lllll is forced downwardly from the upper end position to a lower end position on the seat ll; id ill 75, thereby shutting off communication through the valve .llhl into the flow conductor portion lida below the paclter ii i "With the valve h ll at the lower end position, con'lrnunication is established through the valve between the control line 51 and the flow conductor i l above the valve fill, Fluid pressure is transmitted and llow may occur from the annulus '65 in the valve through tl're ports above the valve lll lll into the bore ti -ll and laterally through the side port 'l'll into the control line tillv filo long as the pressure in the control line and upper por tion of the flow conductor -l-l exceeds the pressure in the production portion 55 of the well bore below the packer, the ball valve will remain at the lower seated position, and fluids may be pumped back and forth as desired through the well system along a flow path defined by the control line ill, the valve 5t), and the flow conductor 4-4, above the valve it When well production is again desired through the flow conductor to the surface, the pressure applied to the control line is de creased until the formation pressure below the packer exceeds the pressure above the ball valve till so that the ball valve is moved to the upper end position shutting off communication into the control line 51 and permit ting upward production flow to again occur to the surface through the valve 50 and the conductor il.

During production and treating procedures in the well the pressure in the annulus as may be controlled through the line tit) and valve oil The annulus fiil above the packer Ml may be maintained liquid filled if desired. in the particular arrangement illustrated in FIG. i., no communication is provided from the annulus 54 into either the control line 511 or the conductor id. Thus, in the system of FIG. ll, utilizing the valve of Fit Fri, the annulus is isolated from the production conduc' tor and control line, production may be had through the main flow conductor 44., and the producing zone below the packer 53 in the well bore may be shut off by pressure in the flow conductor and control line above the valve 50, while circulation as desired is accomplished between the control line and flow conductor above the valve.

FlG. 2 illustrates a well system Ml embodying the in vention which includes the casing 42, the well head dB, and the flow conductor The flow conductor has the surface valve dB for control of flow into and out of the tlow conductor. The packer 53 seals within the casing around the flow conductor below the valve faith The side port "lll in the valve Ell communicates directly with the annulus lid of the well bore above the packer 53, while communication at the wellhead into the annulus is provided through the line so and valve lit. The well in the system oil lFlG. 2 is produced through the flow conductor and the valve till in the same manner as the system ill with well fluids flowing from below the packer upwardly through the flow conductor dd so long as the fluids are at a pressure in excess of both the pressure in the flow conductor above the valve fill and the pressure in the annulus The ball valve tlll may be forced downwardly to shut off production into the l'low conductor by raising the annulus pressure through the line titll to a value suflicient to force the ball valve to the lower seated position. So long as the valve is held on the seat 7d,, the well system may circulated through the flow conductor 1% above the valve filth, through the valve fill, and through the annulus Elsi. luids may flow in either direction through the annulus and flow conductor i l above the valve filh so long as the pressure is maintained above the formation lluids pressure to lreep the valve dill seated at the lower end position.

Another form of well system lltl ll embodying the in vention is shown in HG. llklfll 3. Functionally the s stern till-ll is essentially the same as the system drill in lFl G. l with the exception of the paclcer which is not included in the system llll'll. Lil? components have been given the same reference numerals in the system lll ll as used in the system ill in Flt}. ll. fit flow conductor lllllll having a valve 102 is Connected through the well head into the side port 71 of the valve 50. The conductor 100 performs the same function as the control line 51 but is, however, capable of more flow and thus it would be more adaptable to pumping well tools to and from the valve 50. In the well system 100, so long as the pressure in the well bore exceeds the pressure in the conductor 101, the ball valve 80 is held at the upper end position allowing well fluids to flow to the surface through the valve 50 and the conductor 44. Since no packer is present in the well, the pressure in the well bore within the casing may result from well formation pressure or could be supplied in the line 60 connected into the well head. In this system, maintenance of a pressure in the well bore either from formation fluids or as applied externally through the line 60, permits circulation between the well bore and the flow conductor 44 to the surface irrespective of the source of the well bore pressure. When the pressure in the conductor 101 is raised to a level exceeding the well bore pressure, the valve 80 is forced downwardly on the seal 74 permitting circulation through the well between the flow conductors 44 and 101.

Another form of well system 110 embodying the invention, is shown in FIG. 4 wherein like components are referred to by the reference numerals used with respect to FIGS. 1, 2, and 3. The flow conductor 44 is connected through a cross-over connection 111 at the valve 50 to a parallel flow conductor 112 which includes a surface valve 113 above the well head. As in the other well systems shown, the annulus 54 in the well casing around the flow conductors communicates at the well head with a line 60 having a valve 61 to permit the control of pressure conditions in the annulus. The flow conductors 44 and 112 may extend to suitably packed-off producing zones of the well bore, not shown, which may be defined above an upper dual packer of conventional design sealing within the well casing around both of the flow conductors, with one of the flow conductors being perforated below the dual well packer for production of the well zone immediately below the packer. The other of the two flow conductors may extend through a lower single well packer to a second lower production zone so that the two flow conductors are utilized for the production of separate zones in the well bore, while the mechanism of the cross-over connection and the valve 50 will permit establishment of a circulation pattern between the flow conductors while shutting off the lower portion 44a of the flow conductor 44 below the valve 50. Depending upon well conditions, a suitable standing valve, not shown, may be included in the flow conductor 112 so that when the pressures are adjusted to circulate through the well in the flow conductors through the valve 50, the standing valve will prevent application of the circulation pressure to the well formation communicating with the conductor 112. In operating the well system 110 for dual production from separate producing zones, the higher pressure of the two producing zones is communicated with the flow conductor 44 to achieve simultaneous dual production. The ball valve 80 in the valve 50 must be at its upper position as shown in FIG. 5 for isolating the two flow conductors through the cross-over connection 111 while permitting flow from below the valve 50 through the flow conductor 44 at the same time flow is occurring from the other lower pressure producing zone in the conductor 112. It will be evident that if the higher pressure were in the flow conductor 112, the communication of this pressure through the cross-over flow passage 71 in the valve 50 would force the ball valve to a lower seated position thereby shutting off the flow conductor por- 'tion 44a below the valve 50 to preclude production from the zone communicating with the conductor portion 44a. For circulation between the flow conductors through the valve 50, the pressure may be raised above the ball valve 80 by pumping into the flow conductor 112 until the pressure applied through the passage 71 exceeds the pressure in the flow conductor 44 to force the ball valve downwardly to the lower end position so that pumping circulation may occur between the portion of the flow conductor 44 above the valve 50 and the flow conductor 112. The increase in pressure in the flow conductor 112 closes the standing valve, I: now] not shown, in the flow conductor 112 below the crossover connection so that the producing formation communicating with the conductor 112 is not subjected to the circulation pressure. Once the ball valve 80 is forced to the lower end position, pumping in either direction through the U-shaped flow path defined by the conductors 44 and 112 through the valve 50 may be achieved so long as the pressure is kept to a value sufficient to hold the ball valve 80 on the seat 74. Obviously, the portion 44a of the flow conductor 44 below the valve 50 is not subjected to the circulation pressure.

It will be evident from the description of the well systems of FIGS. 1 and 4, including the valve of FIG. 5, that in each instance, the well valve of the system is located in the first of a plurality of flow passages in the well bore, is operable responsive to a pressure increase in one of the flow passages exterior of such first flow passage, and when so operated, functions to isolate the portion of the first flow passage in the well bore below the valve. The first flow passage above the valve and such other flow passage communicate through the valve. It will additionally be recognized that in the instance of each of the well systems the well valve is in the flow passage which under normal well operating conditions, is subjected to the higher of the pressures to which the valve 50 is exposed. Thus, with respect to the systems of FIGS. 1 and 2, when producing the well, the valve 50 is functioning to shut off the control line 51 in the system 40 and to isolate the well annulus 54 in the system 90. Similarly, in the systems and of FIGS. 3 and 4, the position of the valve in the higher pressure conductor serves to isolate the pair of parallel conductors of each system from each other during production of the well. i

FIGS. 6 and 7 illustrate a valve and cross-over assembly which is particularly useful-in the well systems of FIGS. 1-4. The assembly 120 includes a housing 121 connectible by any suitable means into the flow conductor 44. An internal tubular body portion 122 is provided within the housing 121 concentrically spaced therein defining a central flow passage 123 through the body and an outer annular flow passage 124 around the body in the housing. The body 122 is connected by short conduit section 125 providing a side port communicating the exterior of the valve housing with the central flow passage 123. The central flow passage 123 has an upper principal portion 123a above an internal annular supporting shoulder 131 and a lower reduced portion l23b extending downwardly from the shoulder 131 to an internal annular valve seat 132. The

lower portion 123b of the central flow passage'communicates through ports of 133 in the internal housing portion 122 with the annular flow passage 124. The internal housing 122 has an internal annular locking recess 134 around and near the upper end of the upper central flow passage portion 123a. A removable valve 135 is releasably locked in the central flow passage 123 of the valve assembly 120 for controlling flow to the side port 130. The valve 135 has a cylindrical body 140 provided along its upper end portion with expandable and contractible locking dogs 141 adapted to engage the locking recess 134 for locking the valve in the internal body portion 122. The locking dog arrangement including the locking dogs 141 may comprise any suitable conventional locking mandrel such as those manipulated by wireline techniques as illustrated on page 3,832 of the Composite Catalog of Oilfield Equipment and Services, 1970-71 Edition, published by World Oil, Houston, Tex. The valve body 140 has an external annular recess 142 in which ring seal 143 is disposed for sealing around the valve body within the central flow passage 123. The valve body has a valve member and spring chamber 144 for a vertically movable valve 145 which includes an upper spring retainer flange 150, a valve rod 151, and a valve member 152 provided with an external ring seal 153 for sealing around the valve member within the lower flow passage portion 123b. The valve 145 is biased upwardly by a spring 154 com fined between the upper spring flange 150 and an internal stop flange 152 formed in the valve body 140 at the lower end of the chamber 144. The valve member is movable between an upper end position as in FIG. 6 and a lower end position as in FIG. 7. At the position of the valve in FIG. 6, the valve member 152 is disposed between the side port 130 and the ports 133 communicating with the central passage portion 123b so that the port 130 and the ports 133 are isolated from each other. Thus, at this valve position in the well system flow may occur from the lower flow conductor portion 44a upwardly and outwardly through the ports 133 into the annular space 124 from which the fluids flow upwardly into the conductor 44. The flow through the well conductor 44 is isolated from the flow passage connected with the side port 130, which may be the well annulus or another flow conductor. The upward force on the valve member 145 is the combination'of the force of the spring 154 biasing the valve upwardly and the pressure in the well fluids in the flow passage portion l23b below the valve member 152. An increase in the pressure applied through the side port 130 tothe valve member 152 above the ring seal 153 to a level at which the force of the pressure exceeds the upward force on the valve member moves the valve to a lower end position against the seat 132. At this lower end po sition, the lower conductor portion 44a is isolated from the well conductor above the seat 132, while the ports 133 and the side portl30 communicate through the central flow passage portion 12% so that the well may be circulated between the upper portion of the flow conductor 44 above the valve and the side port 130. So long as the pressure above the valve member is sufficient to hold it at the lower end position of FIG. 7, the well may be circulated with the flow conductor portion 44a below the valve isolated. When the pressure above the valve member is reduced to a level at which the force of the spring and the pressure below the valve member may lift the valve member, the valve member is returned to the upper end position to again effectively close the side port and permit well flow through the flow conductor 44a from below the valve. Thus, well systems including the valve 120 are responsive to casing, control line, or parallel tubing, depending upon the particular well system, for shutting off the lower portion of the flow conductor containing the valve and establishing well circulation through the valve. The valve cannot be opened or moved to a circulating position by increasing the pressure in the flow conductor containing the valve.

FIGS. 8 and 9 show another valve and cross-over assembly which may be used in well systems similar to those of FIGS. 3 and 4. The system includes a flow conductor 161 having a lower portion 161a which may extend to a producing formation along the well bore. The valve assembly includes a removable spring-biased valve 162 which has a valve member 163 supported on a valve rod 164 biased in an upward direction by a spring 165. The lower flow conductor portion has an annular valve seat engageable by the valve member 163 at a lower end position for isolating the conductor portion 161a below the valve assembly. A by-pass flow line 171 is connected at opposite ends into the flow conductor 160 around the valve 162. The lower end of the by-pass line connects into the flow conductor 160 above the valve member 163 when the valve member is at a lower end seated position as illustrated in FIG. 9. The conductor 161 communicates through a crossover connection 172 into another flow conductor 173 which extends upwardly to the well head and downwardly to a producing formation, not shown, communicating with the well bore. The flow conductors 161 and 173 extend through a suitable, conventional dual packer 174 which seals within the well casing 42 around both of the flow conductors. The flow conductor 173 and the lower portion 161a of the conductor 161 may extend to separate producing zones in the well bore to permit dual production in the well system. The flow conductor 173 is preferably provided with a standing valve, not shown, at a depth below that portion of the conductor shown in FIG. 8 to permit production upwardly through the flow conductor while precluding downward flow through the conductor when the well is being circulated through the valve assembly 160.

In the operation of the valve system 160, with the valve position as illustrated in FIG. 8 the well may be produced through both of the flow conductors simultaneously. Well fluids entering the flow conductor 173 flow through the conductor directly to the surface. Well fluids entering the lower conductor portion 161a flow upwardly in the conductor to the junction of the conductor with the by-pass line 171. The valve member 163 diverts the well fluids into the by-pass line through which they flow around the valve 162 and back into the flow conductor 161 above the valve and to the surface. The valve member 163 at the position of FIG. 8 prevents communication between the flow conductors 161 and 173. The normal production pressure in the con- When well circulation from the surface through the flow conductors 161 and 173 and the valve assembly 160 is desired, the relative pressures in the flow conductors are adjusted as by increasing the pressure in the conductor 173 to a value at which the downward force on the valve member 163 exceeds the upward force on the spring 165 and the pressure in the conductor portion 161a below the valve member. The valve member 163 is forced downwardly to the lower end position of FIG. 9 at which the valve member seats on the valve seat 170.

At the lower end position of the valve member the lower conductor portion 161 is isolated, and the flow conductors 161 and 173 communicate through the valve bore 166 above the valve member 163 and the cross-over connection 172. Downward flow in the conductor 173 is prevented by virtue of the standing valve in the conductor, not shown. 80 long as sufficient pressure is maintained above the valve member 163 to keep it at the lower end position, flow may occur from the well head in either direction through the flow passage system including the flow conductors 161 and 173. For example, if fluids are pumped into the well through the conductor 161, they pass downwardly in the conductor, through the bypass line 171, into the valve bore 166 above the valve member 163, and across through the cross-over connection 172 into the flow conductor 173 through which the fluids return to the surface. The reverse of this flow pattern is followed by fluids pumped into the flow conductor 173 at the surface with returns moving upwardly in the flow conductor 161. There is no communication with the annulus 54 during such well circulation. After the well has been serviced as desired, reduction in the pressure in the flow conductor 173 permits the valve member. 163 to return upwardly to the upper end position at which the flow conductors are again isolated from each other, and simultaneous well production may occur in the conductors. The annulus 54 may be maintained liquid full in view of the fact that there is no communication between the annulus and either of the flow conductors.

Another form of well system embodying the invention is illustrated in FIGS. and 11. A pair of flow conductors 180 and 181 are disposed in the casing 42 through a dual packer 183 extending to producing formations, not shown. The flow conductor 180 may include a standing valve, not shown, to prevent back flow during well circulation between the flow conductors. The flow conductors are interconnected through a valve assembly 184 by a cross-over connection 185. The valve assembly includes a removable valve 190. The valve has a valve stem 191 which is longitudinally movable in a valve bore 192 which communicates at the upper end thereof with the flow conductor 181 and at the lower end with a lower portion 181a of the flow conductor 181. The valve stem is biased upwardly by a spring 193. A pair of spaced upper and lower valve members 194 and 195 are supported on the valve stem above and below the cross-over connection 185 between the flow conductors. The lower flow conductor portion 181a has an annular valve seat 200 engageable by the lower valve member 195 when the valve stem and members are at a lower end position. A side port 201 in the conductor 181 communicates the well annulus 54 around the flow conductors with the valve bore 192 above the upper valve member 194 whereby the valve functions responsive to the annulus pressure. A

by-pass line 202 connects the flow conductor 181 above the valve 190 with the lower flow conductor portion 181a below the valve member 195. The by-pass line communicates through a port 203 at its upper end with the flow conductor above the valve and through a port 204 at its lower end with the lower portion of the valve bore 192. The port 204 is spaced above the valve seat 200 so that the valve member 195 when on the seat 200 is below the port 204. Well fluids from a formation communicating with the flow conductor flow directly to the well head. When the valve is at the position of FIG. 10, the well fluids from a formation communicating with the lower flow conductor portion 181a flow through the side port 204, the 'by-pass line 202 and into the upper flow conductor portion 181 through the side port 203, thereby passing the valve 190. The port 201 communicates the casing annulus 54 around the flow conductors with the valve bore 192 above the upper valve member 194. So long as the force of the pressure within the flow conductor 181 below the valve member 195, combined with the force of the spring 193, exceeds the force of the pressure applied from the casing annulus through the port 201 to the upper valve member 194, the valve remains at the upper end position of FIG. 10, isolating the two flow conductors for simultaneous production through both conductors. The pressure within the flow conductor 180 as applied to the valve members through the cross-over connection does not affect the valve; thus, regardless of the pressure in such flow conductor, the valve position is not altered. The upper and lower valve members are of the same cross sectional area, and thus the upward force applied to member 194 is counterbalanced by the downward force applied to member 195. The upper valve member 194, irrespective of the valve position, always remains between the cross-over connection 185 and the port 201 to the casing annulus precluding communication at all times between the casing annulus and either of the flow conductors. When communication is desired for fluid flow between the flow conductors 180 and 181, the pressure relationship between the flow conductor 181 below the lower valve member 195 and the casing annulus pressure is changed, such as by increasing the casing annulus pressure until the force from such pressure as applied through the port 201 to the upper valve member 194 exceeds the force of the spring 193 and the force of the pressure in the flow conductor 181 applied to the lower valve member 195. The valve is moved downwardly to the lower end position shown in FIG. 11, at which position the lower flow conductor portion 181a is isolated by the seating of the lower valve member 195 on the valve seat 200 below the port 204 leading to the by-pass line 202. With the valve member 195 below the port 204 the conductors 180 and 181 communicating through the valve bore 192 which connects with the cross-over connection 185 and the port 204. Thus, fluid flow may occur between the flow conductor 180 and the upper portion of the flow conductor 181 through the port 203, the bypass line 202, the port 204, the valve bore 192 between the lower valve member 195 and the upper valve member 194, and the cross-over connections 185 into the flow conductor 180. The casing annulus remains isolated from the flow conductors. So long as the casing annulus pressure is maintained sufficiently above the pressure in the flow conductor portion 181a below the lower valve member 195,-fluid may flow in either direction between the flow conductors 180 and 181. When return of the valve to the upper end position of FIG. is desired, the casing pressure is reduced to permit the spring 193 and the pressure below the lower valve member 195 in the lower conductor portion 181a to lift the valve back upwardly. Thus, the valve system shown in FIGS. 10 and 11 permits the isolation of parallel flow conductors from each other and the communication of such flow conductors with each other responsive to casing pressure while isolating the lower portion of the flow conductor containing the valve from the remain der of the well system, at all times isolating the casing annulus pressure from both of the flow conductors.

FIGS. 12 and 13 illustrate a still further form of valve arrangement in a well system which permits dual production at one valve position and communicates the casing annulus and one flow conductor while isolating the other flow conductor at another valve position. Referring to FIGS. 12 and 13, a pair of flow conductors 210 and 211 are supported in the casing 42 through a dual well packer 212 extending in the well to dual production Zones, not shown. The flow conductor 210 includes a standing valve, not shown, to prevent backflow during well servicing procedures into the producing formation communicating with the flow conductor. The flow conductors communicate through a crossover connection 213. A valve 214 is removably sup ported in the flow conductor 211 for controlling cornmunication with the cross-over connection. The valve includes a stern 215 supporting a pair of spaced upper and lower valve members 220 and 221, respectively, movable along a bore portion 222. An annular valve seat 223 is disposed at the lower end of the bore 222 to cooperate with the lower valve member 221 for shutting off communication to the lower flow conductor portion 211a. A by-pass line 224 is connected into the flow conductor 211 around the valve 214. The by-pass line communicates with the flow conductor 211 through an upper' port 225 above the valve 214 and through a lower port 230 with the valve bore 222 above the valve seat 223 below the upper end position of the lower valve member 221. The valve stem 215 is biased upwardly by a spring 216. A port 231 in the flow conductor 211 communicates with the valve bore 222 above the upper valve member 220. At the upper position of the valve 214 shown in FIG. 12, the flow conductors 210 and 211 are open to the surface and are isolated from each other and from the casing annulus 54. The upper valve member 220 is disposed in the bore 222 between the port 231 and the cross-over connection 213, precluding casing annulus communication with the conductor 210. The lower valve member 221 is disposed in the bore 222 between the port 230 and the cross-over connection, preventing communication between the flow conductors 210 and 211. Any pressure changes in the flow conductor 210 communicated through the cross-over connection are applied equally to the upper valve member 220 and the lower valve member 221 so that pressure variations in the flow conductor 210 do not affect the position of the valve when the valve is at the upper end position. Fluids may flow from the lower flow conductor portion 211a upwardly through the lower port 230, the by-pass line 224, and the upper port 225 into the upper flow conductor portion 211 through which the fluids flow to the well head. A sufiicient increase in the casing annulus pressure applied through the port 231 to the upper valve member 220 forces'the valve downwardly against the combined force of the spring 216 and the pressure in the flow conductor 211 as applied upwardly to the lower valve member 221. The valve stem 215 along with the upper and lower valve members 220 and 221 moves downwardly until-the lower valve member seats on the annular surface 223 below the port 230. At such lower valve position the upper valve member is disposed below the cross-over connection 213 so that the well annulus 54 communicates with the flow conductor 210 through the port 231, the bore 222 above the upper valve memher and the cross-over connection. The movement of the upper valve member below the cross-over connection prevents communication between the flow conductors 210 and 211 while the movement of the lower valve member against the seat 223 isolates the lower flow conductor portion 211a. At this lower valve position the upward forces on the valve are the force of the spring 216 and the force of the pressure in the lower conductor portion 21 la below the lower valve member 221. The downward force on the valve is provided by the annulus pressure in the bore 222 above the upper valve member 220. So long as this downward force exceeds the upward force on the valve, the well may be circulated in either direction between the flow conductor 210 and the casing annulus 54. During such circulation the upper and lower sections of the flow conductor 211 are isolated from each other and from the conductor 2 10 and the'annulus 54. When return of the valve upwardly is desired, the pressure is lowered in the casing annulus and the flow conductor 210 to a level sufficient to permit the spring 216 and the pressure in the lower flow conductor portion 211a to return the valve upwardly so that the well may again be produced through both of the flow conductors 210 and 211.

FIGS. 14 and 15 show a valve arrangement which functions in the same way as the valve system of FIGS. 12 and 13, utilizing, however, a different valve design. The well flow conductor system, including the bypass line 224, shown in FIGS. 14 and 15, is identical to that shown and described with reference to FIGS. 12 and 13 and, thus, identical reference numerals to those in FIGS. 12 and 13 are used in FIGS. 14 and 15 for identical components of the well system. A removable valve 240 is supported in the flow conductor 211 for controlling the flow functions of the flow conductor 211 and the communication between the casing annulus and the flow conductor 210. The'valve includes a stem 241 biased upwardly by a spring 242. A valve member 243 is supported on the stem for movement between the upper end position shown in FIG. 14 and the lower end position of FIG. 15. The valve member has a solid lower portion 244 supporting a pair of longitudinally spaced external annular ring seals 245 and 250 which seal around the lower valve member portion with the surface of the bore 222. The valve member has an upper portion 251 provided with a chamber 252 and a lower port 253 and upper ports 254 opening into the chamber. A ring seal 255 is disposed around the upper valve member portion between the port 253 and the ports 254. At the upper position of the valve member shown in FIG. '14, one zone of the well is produced through the flow conductor 210 while another zone is produced through the lower flow conductor portion 211a, the by-pass line 224 around the valve 240, and the upper portion of the flow conductor 211. The ring seals 245 and 250 on the valve member 243 are above 

1. A well system for producing and servicing a well comprising: means defining a plurality of flow passages in a well; means defining a cross-over connection between at least two of said flow passages; and valve means disposed in a first of said flow passages for controlling communication between at least two of said flow passages through said cross-over connection, said valve means isolating said two flow passages from each other at a first position of said valve means and communicating said two flow passages with each other at a second position of said valve means, said valve means being movable between said positions responsive only to a pressure (valve) value exterior of said first flow passage in excess of the pressure in said first flow passage, said valve permitting flow in both directions through the cross-over connection while in said second position .
 2. A well system in accordance with claim 1 wherein said valve means at said second position isolates the portion of said first flow passage below said valve means from the remainder of said flow passages while communicating at least said two flow passages.
 3. A well system in accordance with claim 2 wherein the fluid pressure in said first flow passage during normal well production at said first position of said valve means is higher than the pressure exterior of said first passage, a relative increAse in which moves said valve means to said second position.
 4. A well system in accordance with claim 2 wherein said first flow passage is defined by a flow conductor adapted to be supported in a well, and said valve means is disposed in said flow conductor at means including said cross-over connection to communicate said connection with said flow conductor when said valve means is at said second position and to isolate said flow conductor below said valve means from said connection when said valve means is at said first position.
 5. A well system in accordance with claim 4 including a landing nipple comprising a hollow body member spaced within said flow conductor defining a bore in which said valve means is disposed, said cross-over connection opening into said bore, means defining a valve seat in said body member for engagement by said valve means at said second position, and means defining a port communicating said bore of said body member with a space in said flow conductor around said body member whereby fluid flows through said space from below said valve means into said flow conductor above said valve means when said valve means is at said first position.
 6. A well system in accordance with claim 2 wherein first and second flow passages are defined by two flow conductors interconnected by said cross-over connection, said flow conductors being isolated from the casing annulus of said well, said valve means being engaged in a first of said conductors defining said first flow passage, said first conductor having a by-pass for flow around said valve means when said valve means is at said first position between said by-pass and said cross-over connection and said by-pass permitting communication through said cross-over connection to said second flow conductor from said first flow conductor above said valve means when said valve means is at said second position, said valve means being movable from said first to said second position by a pressure in said second flow conductor higher than the pressure in said first flow conductor.
 7. A well system in accordance with claim 2 wherein first and second flow passages are defined by first and second flow conductors and a third flow passage is defined by the casing annulus in said well around said flow conductors, said cross-over connection interconnecting said first and second flow conductors port means provided in said first conductors spaced above said cross-over connection communicating with said third flow passage, a by-pass line connected at opposite ends at spaced locations into said first flow conductor, the lower end of said by-pass line connecting into said first flow conductor at a location spaced below said cross-over connection, said valve means being disposed in said first flow conductor at a location permitting fluid flow around said valve means from below said valve means to above said valve means through said by-pass line when said valve means is at a first position, said valve means including an upper valve member disposed and movable between said cross-over connection and said port to said third flow passage whereby said third flow passage is isolated at all times from said cross-over connection and said valve member is responsive to pressure in said third flow passage, and said valve means includes a second valve member movable with said first valve member and disposed at said first position of said valve means between said cross-over connection and said lower end of said by-pass line into said first flow conductor whereby said flow conductors are isolated from each other at said first position of said valve means, said second valve member moving at the said second position of said valve means to a position below said connection of said lower end of said by-pass line into said first flow conductor for communicating said first and second flow conductors with each other while isolating the lower portion of said first flow conductor below said valve means.
 8. A well system in accordance with claim 2 wherein first and second flow passages are defined by flow conductors in said well and a third flow passages is defined by a well annulus around said flow conductors, said cross-over connection interconnecting said first and second conductors, said first conductor having a port spaced above said cross-over connection communicating said conductor with said third flow passage, said valve means being disposed in said first flow conductor, said first flow conductor having a by-pass line connected at an upper end into said flow conductor above said valve means and at a lower end into said flow conductor below said cross-over connection, said valve means having spaced first and second valve members, at said first position of said valve means said first valve member being disposed between said port to said third flow passage and said cross-over connection and said second valve member being disposed between said cross-over connection and the connection of said lower end of said by-pass line into said first flow conductor whereby said first and second flow conductors are isolated each from the other and said third flow passage is isolated from both of said flow conductors, said valve means being movable to said second position at which said first valve member is disposed between said cross-over connection and said connection of said lower end of said by-pass line into said first flow conductor and said second valve member is disposed in said first flow conductor below said connection of said lower end of said by-pass line to said flow conductor whereby said third flow passage and said second flow conductor communicate with each other through said cross-over connection and said side port in said first flow conductor, said lower portion of said first flow conductor is isolated from the upper portion of said conductor, and said upper portion of said first flow conductor is isolated from said second flow conductor, said valve being movable to said second position responsive to a pressure in said third flow passage in excess of the pressure in said first flow conductor.
 9. A well system in accordance with claim 2 wherein first and second flow passages are defined by first and second flow conductors and said cross-over connection interconnects said conductors, said first conductor having a port spaced above said cross-over connection communicating with a third flow passage defined in said well around said flow conductors, said valve means being disposed in said first flow conductor, a by-pass line along said first flow conductor around said valve means connected at an upper end to said first flow conductor above said valve means and at a lower end below said cross-over connection, said valve means including a movable valve member for isolating said first and second flow conductors from each other and from said third flow passage at a first valve position while allowing upward flow along said first flow conductor and said by-pass line, and said valve member at a second position communicating said second flow conductor with said third flow passage through said cross-over connection while isolating upper and lower portions of said first flow conductor from each other and from said second flow conductor and said third flow passage, said valve member being movable to said second position responsive to a pressure in said third flow passage in excess of the pressure in said first flow conductor.
 10. A well system in accordance with claim 2 wherein first and second flow passages are defined by first and second flow conductors and said cross-over connection interconnects said flow conductors, a third flow passage is defined by the annular space in said well around said flow conductors, said first flow conductor having a side port spaced above said cross-over connection communicating with said third flow passage, said valve means being disposed in said first flow conductor, a by-pass line connected along said first flow conductor around said valve means, the upper end of said by-pass line being connected into said first flow conductor above said valve means and the lower end of said by-pass line being connected into said first flow conductor at a location spaced below said cross-over connection, said valve means including a valve member having means at a first position for isolating said first and second flow conductors from each other and from said third flow passage while permitting flow along said first conductor and by-pass line, said valve member having means at a second position communicating said third flow passage with the portion of said first flow conductor above said valve means while isolating the portion of said first flow conductor below said valve means and isolating said second flow conductor from said first conductor and said third flow passage, said valve member being movable to said second position responsive to a pressure in said third flow passage in excess of the pressure in said first conductor.
 11. A well system in accordance with claim 2 wherein said first and second flow passages are defined by first and second flow conductors interconnected by said cross-over connection and a third flow passage is defined by the annular space around said flow conductors, said first flow conductor having a side port above said cross-over connection communicating with said third flow passage, said valve means being disposed in said first flow conductor at said cross-over connection, a by-pass line connected into said first flow conductor, the upper end of said by-pass line being connected into said conductor above said valve means, and the lower end of said by-pass line being connected into said conductor at a location spaced below said cross-over connection, said valve means including a valve member movable in said flow conductor and having means for isolating said first and second flow conductors and said third flow passage from each other at a first position while permitting flow along said first conductor and by-pass line, and at a second valve member position for communicating said first conductor above said valve means with said second flow conductor through said cross-over connection while isolating said third flow passage and said first conductor below said valve means, said valve member being movable to said second position responsive to a pressure in said third flow passage in excess of the pressure in said first flow passage.
 12. A well system in accordance with claim 2 wherein first and second flow passages are defined by first and second flow conductors interconnected by said cross-over connection and a third flow passage is defined by an annular space in said well around said flow conductors, said first flow conductor having a port spaced above said cross-over connection communicating with said third flow passage, said valve means being disposed in said first flow conductor, a by-pass line connected into said first flow conductor from above said valve means to a location spaced below said cross-over connection, said valve means including a valve member having means for isolating said first and second flow conductors and said third flow passage from each other while permitting flow along said first conductor and by-pass line at a first valve member position and at a second valve member position isolating a lower portion of said first conductor below said valve means while communicating said flow conductor above said valve means with said third flow passage and with said second flow conductor through said cross-over connection, said valve member being movable to said second position responsive to a pressure in said first flow passage below the pressure in said third flow passage.
 13. A well system in accordance with claim 2 wherein said first and second flow passages are defined by first and second flow conductors and said cross-over connection connects said conductors, means for supporting a valve in said first conductor at said cross-over connection, said valve being movable between a first position at which said first and second flow conductors are isolated from each other and a second position at which said first conductor above said valve is communicated with said second flow conductor and the portion of said first conductor below said valve is isolated, and a valve in said second flow conductor at said cross-over connection movable between a first position at which said flow conductors communicate through said cross-over connection and a second position at which said flow conductors are isolated from each other at said cross-over connection.
 14. A well system in accordance with claim 13 wherein said valve in said second flow conductor is a sliding sleeve valve.
 15. A well system in accordance with claim 2 including means defining first and second flow passages comprising first and second flow conductors interconnected by said cross-over connection, said valve means being releasably lockable in either of said flow conductors at said cross-over connection, a by-pass line connected into each of said flow conductors from above said valve means to a location spaced below said cross-over connection, said valve means having a valve member disposed at a first position between said cross-over connection and the connection of the lower end of the by-pass line into the flow conductor in which said valve means is locked whereby at said first position of said valve member said first and second flow conductors are isolated from each other, and said valve member being movable to a second position responsive to a pressure in the other flow conductor in excess of the pressure in the flow conductor in which said valve means is locked, said valve member isolating the lower portion of the flow conductor in which said valve means is locked and communicating the upper portion of such flow conductor with the other flow conductor through said cross-over connection.
 16. A well system for producing and servicing a well comprising: means defining a plurality of flow passages in said well for well fluids and service fluids flow; means for cross flow between at least two of said flow passages; and means for supporting a valve in a first of said flow passages for selectively isolating and communicating said two passages connected with said cross-flow means for flow in both directions responsive only to a pressure exterior of said first flow passage in excess of the pressure in said first flow passage.
 17. A well system in accordance with claim 16 including a flow control valve in said valve supporting means, said valve being movable between a first valve position at which said two flow passages communicatable through said cross flow passage are isolated from each other and a second valve member position at which said two flow passages communicate with each other, said valve being movable between said positions responsive to a pressure differential across said valve means between said first flow passage and one of said flow passages other than said first flow passage.
 18. A well system in accordance with claim 16 wherein said two flow passages connected with said means for cross flow are defined by first and second flow conductors, said first flow conductor having a side-pocket landing nipple having a side pocket for said valve and communicating with said means for cross flow.
 19. A well system in accordance with claim 18 wherein said second flow conductor includes a side-pocket type landing nipple, and the side pockets of both of said landing nipples communicate through said means for cross flow.
 20. A well system in accordance with claim 19 wherein said landing nipples are longitudinally aligned with each other.
 21. A well system in accordance with claim 19 wherein said landing nipples are displaced longitudinally from each other and nested together in an over-under relationship, and said means for cross flow is defined by conduit means extending longitudinally between side ports in said side pockets of said landing nipples.
 22. A well system in accordance with claim 16 wherein said two flow passages are defined in an integral unit foR connection with first and second flow conductors, one side of said unit having a longitudinally extending side-pocket type landing nipple and the other side of said unit having a longitudinal flow passage, and said unit having said means for cross flow connecting the side pocket of said landing nipple and said longitudinal flow passage.
 23. A well system in accordance with claim 16 wherein said two flow passages are defined in an integral unit having side-by-side side-pocket type landing nipples formed therein, the side pockets of said nipples communicating through said means for cross flow whereby said valve is positionable in either of said side pockets for controlling flow between said landing nipples.
 24. A duplex mandrel for a crossover system for use in a dual string of well tubing comprising, a pair of mandrels, each of said mandrels adapted to be connected in one of the well tubings, each of the mandrels including an open bore therethrough and a pocket for flow control devices offset from the bore, said mandrels being connected together, and a fluid conduit extending between the pockets.
 25. A duplex mandrel for a crossover system for use in a dual string of well tubing comprising, a pair of mandrels, each of said mandrels adapted to be connected in one of the well tubings, each of the mandrels including an open bore therethrough aligned with the connected well tubing, and including a sidepocket offset from the open bore, said mandrels being connected together with the open bores being positioned side by side and the side pockets being positioned side by side, and a fluid conduit extending between the side-pockets. 